The present invention relates to a lamp unit assembling method and a lamp unit mounting structure for mounting a lamp unit, such as a room lamp, in a lamp mounting window of an interior wall member, such as a roof trim, which covers a vehicle body panel.
Generally, when lamp units, such as a room lamp and a courtesy lamp, are mounted on interior wall members, such as a roof trim and a door trim, each of the lamp units is mounted in a corresponding one of lamp mounting windows opened in the interior wall members.
FIGS. 23 and 24 are a perspective view and a sectional view illustrating a related automobile roof assembling method disclosed in Japanese Unexamined Utility Model Publication Hei. 4-57454 and a related lamp unit assembling structure disclosed in Japanese Unexamined Patent Publication Hei. 5-131882, respectively. As shown in FIG. 23, a roof harness 37 is first mounted under a body roof 2 serving as a body panel of a vehicle body 1. Subsequently, a roof trim 30 serving as an interior wall member for covering the body roof 2 is mounted thereunder.
Further, connectors 40 and 41 of the room harness 37 are temporarily and downwardly drawn together with cables 37a and 37b out of a room lamp mounting window 31a and a map lamp mounting window 31b, which serve as the lamp mounting windows opened in the roof trim 30, and then connected to the lamp units, such as the room lamp 35 and the map lamp 36, respectively. Subsequently, the cables 37a and 37b are placed on the roof trim 30 through a room lamp mounting window 31a and a map lamp mounting window 31b. Then, the room lamp 35 and the map lamp 36 are respectively mounted in the room lamp mounting window 31a and the map lamp mounting window 31b by screwing. Finally, non-electric components, such as a rearview mirror 38 and a sun visor 39, are mounted on the roof trim 30. Thus, an automobile roof is assembled.
For example, the room lamp 35 serving as the lamp unit mainly comprises a housing 34, a bulb (that is, an electric bulb) 44, and a cover lens 33, as shown in FIG. 24. The bulb 44 is inserted into between bus bars 43, 43 serving as bulb contacts fixed to the housing 34. One of the bus bars 43, 43 is connected to a room-lamp-side connector 45. A tapping screw 42 for fixing the room lamp 35 to the roof trim 30 is mounted to the housing 34. A mounting hole 32, into which the tapping screw 42 is inserted, is provided in the roof trim 30.
Moreover, a switch unit (not shown), which accommodates a switch circuit connected to the bus bar 43 and is enabled to switch between ON and OFF states of the bulb 44, is attached to the room lamp 35. Furthermore, according to the specification of a vehicle, a reflector designed in consideration of the luminous intensity distribution of the bulb 44 may be attached to a vehicle body panel side portion of the housing 34 in addition to the aforementioned constituent elements.
FIG. 25 is a schematic view illustrating a mounting structure for related lamp units disclosed in Japanese Unexamined Patent Publication Hei. 1-307108. FIG. 26 is a sectional view illustrating a primary part of this structure. As illustrated in FIGS. 25 and 26, a room lamp 57 and a spotlight 58 are lamp units respectively mounted in lamp mounting windows 55 and 56 opened in a roof trim 53 serving as an interior wall member that covers a body roof 52.
As shown in FIG. 25, a flat cable harness 51 fixed too circuit elements to an insulating sheet is wired between the room lamp 57 and the spotlight, so that the room lamp 57 and the spotlight 58 are integrally formed to constitute a roof harness 50.
Thus, since the components to be roof-mounted, such as the room lamp 57, the spotlight 58, the rearview mirror (not shown), and a sun visor, on the roof trim 53 is preliminarily assembled to form a roof module and then the module is mounted on the body roof 52, an operation of mounting components on the roof trim 53 can be omitted when a low-workability roof trim is mounted, thereby facilitating an assembling operation.
Meanwhile, according to the related automobile roof assembling method illustrated in FIGS. 23 and 24, for example, when the aforementioned related room lamp 35 is mounted onto the roof trim 30, it is necessary to temporarily and downwardly draw the connector 40 connected to the cable 37a of the roof harness 37 from the room lamp mounting window 31a and to then connect the connector 40 to a room-lamp-side connector 45 of the room lamp 35. Further, upon completion of connecting the connector 4 thereto, it is necessary to place the connectors 40 and 45 on the roof trim 30 together with the cable 37a of the roof harness 37 through the lamp mounting window 31a and to then fix the room lamp 35 to the lamp mounting window 31a by using the tapping screw 42. This complicates the assembling operation that is overhead work performed in a narrow working space. Consequently, good workability is difficult to obtain.
Thus, the module is preliminarily formed by mounting the components to be roof-mounted, such as the room lamp 35, the map lamp 36, the rearview mirror 38, and the sun visor 39, onto the roof trim 30. Then, the module is mounted on the body roof 2. Consequently, the operation of mounting the components on the roof trim can be omitted. This facilitates the assembling operation.
However, when the module is mounted thereon, the body roof trim 30 covers and hermetically seals the bottom-side portion of the body roof 2, so that an enclosed chamber is formed therein. Therefore, the connectors 40 and 41 placed in the enclosed chamber cannot be connected to the room lamp 35 and the map lamp 36. Thus, the following method is considered. The connectors 40 and 41 at the side of the body roof 2 are fixed, as employing reception connectors, at places respectively portions corresponding to the room lamp 35 and the map lamp 36 at the side of the module, simultaneously with the mounting of the module thereon. However, the mounting accuracy of the module (or the roof trim 30) is significantly low, as compared with the connecting accuracy of the connectors 40 and 41. Actually, it is difficult to connect the connectors 40 and 41 to the connector portions with good accuracy. Especially because of the fact that the connection states of the connectors 40 and 41 cannot be visually checked by a worker, this conventional method has encountered a problem of poor connection reliability.
Further, the room lamp 35 has a lamp function portion, that is, comprises a portion that the housing 34, the tapping screw 42, the bus bar 43, the bulb 44, the connectors 40, 45 and the switch unit, as described above. Thus, the number of components of the functional portion of the room lamp 35 is large. When the reflector is attached thereto, the number of components thereof increases still more.
Further, as the manufacturing costs of the components increase, the assembling thereof is complicated more and more. Consequently, it is difficult to reduce the manufacturing cost of the lamp unit.
On the other hand, in the case of the related lamp unit mounting structure illustrated in FIGS. 25 and 26, when a roof module obtained by preliminarily inserting the room lamp 57 and the spotlight 58 into the lamp mounting windows 55 and 56 of the roof trim 53 is mounted onto the body roof 52, the roof trim 53 is assembled and fixed to the body roof 52, as shown in FIG. 26. Simultaneously, the room lamp 57 is screwed into and fixed to the body roof 52. Moreover, the room lamp 57 is fitted into the opening formed in the body roof 52. Thus, the lamp unit is mounted onto the roof trim.
Thus, in the case that the roof trim 3, whose mounting accuracy is poor, causes positional displacement with respect to the body roof 52 when the roof trim (or roof module) 53 is assembled to the body roof 52 in a vehicle body assembly line, the room lamp 57 inserted into the lamp mounting window 55 of the roof trim 53 causes positional displacement with respect to the screw holes and the openings provided in the body roof 52. Thus, there is a possibility that the room lamp 57 cannot be mounted onto the body roof 52.
Further, even when the room lamp 57 is mounted thereon, a gap S is provided between the peripheral edge of the cover lens of the room lamp 57 and the periphery of the lamp mounting window 55 so that the width of the gap S is equal to an amount of positional displacement of a center mounting axis O1 of the room lap 57 mounted on the body roof 52 with respect to a center axis O2 of the opening, that is, the lamp mounting window 55, as illustrated in FIG. 26. This deteriorates the appearance of the lamp unit. Thus, this related mounting structure has encountered another problem of degradation in quality of the lamp unit.
That is, the related mounting structure for the lamp unit illustrated in FIG. 25 has encountered problems that the assembling workability at the assembling of the roof trim 53 and the body roof 52 is not good, and that an assembling failure is liable to occur.